TRACTOR

PURPOSE:To enable the traction of small-size but heavy freight by pressing a driving wheel, with the coupling part as a fulcrum, against a travelling face. CONSTITUTION:A tractor 10 comprises a frame 1, which has a driving wheel 8 rotatable on a travelling face 11, and a coupling part 2 with an object to be shifted 15, which is provided at one end of the frame 1. A motor 3, which is mounted a distance larger than that between the driving wheel 8 and the coupling part 2 apart, is provided at the other end of the frame 1, and also the object 15 to be shifted is coupled with the tractor 10 by a coupling shaft 16. When the motor 3 is rotated clockwise, the driving wheel 8 also rotates in the same direction through a chain 9, and the force of moving the object 15 to be shifted works. Besides, if the mass of the object 15 to be shifted is large, the driving wheel 8 does not rotate, and the torque shown by an arrow B works on the object 15 to be shifted. By this torque, the force of pressing the driving wheel 8 against the travelling face 11 with the coupling shaft 16 as a fulcrum occurs, and the contact face pressure increases, and the driving wheel 8 rotates, and the object 15 to be shifted moves.